I mentioned above that one of my trips I wandered about for three weeks, then used my last week to get back to starting point so I would not miss my flight. My goal at the start was to see some of the interior of Iceland, but that was accomplished during week one, so wandered about for the rest. My route in red, below.
I fully agree with DJB, start out with some overnights, then see how you like it. Then maybe a few week long trips.
A lot of people will buy a touring bike, buy panniers, etc., and then after a week long tour that they did not enjoy, then put everything up for sale when they get home.